1. Field of the Invention
The present invention relates to delivery conduits used in systems that provide positive pressure ventilation therapy. In particular, the present invention relates to a method of forming a connector on a conduit and a sleeve used in the method that allows flexible conduits to be joined and sealed to a thermoplastic connector, allowing for gases to be supplied to the conduit.
2. Summary of the Prior Art
Administration of positive pressure ventilation is a common method of treating Obstructive Sleep Apnoea syndrome and Upper Airway Resistance syndrome. Some forms of delivery systems that can be used for ventilation therapy are; CPAP (Continuous Positive Airway Pressure), VPAP (Variable Positive Airway Pressure) and BiPAP (Bi-level Positive Airway Pressure).
The delivery of gases to the patient requires, in the very least, a nose, mouth, or face mask fitted to the patient with a connection via a flexible gases delivery conduit to a gases flow generator. One requirement of the delivery conduit is to provide humidified air at a particular pressure to the patient, via the mask. The conduit therefore requires connectors at each end that provide effective sealing and connection of the conduit to the mask, humidifier and/or air flow generator of the positive pressure ventilation system, so that there is no or low pressure loss along the delivery conduit.
There are a variety of methods for fitting a connector to a flexible helically wound conduit, such as the tubing disclosed in U.S. Pat. No. 584,223. This patent discloses a conduit that is a tube having a helically wound support bead between inner and outer walls. A helically wrapped electrical resistance heating conduit is disposed adjacent to the inner wall, in good heat transfer relation to fluid and/or air that flows within the tube. The majority of these connections are made by threading the connector onto the conduit and then gluing the connector to the conduit. For example, U.S. Pat. No. 3,963,856 discloses a connection or fitting that is bonded to a conduit or tubing. The fitting has an internal thread that is simply threaded onto the external bead or wall of the tubing. Here it is disclosed that the bond may be adhesive or of the heat seal type. A further other commonly used method is to mould the connector directly onto the conduit.
The abovementioned methods are operator intensive and/or may result in the conduit being damaged. Usage and bending of the flexible conduit may cause loss of adherence from the glue and it may also cause breakages where the conduit is stressed during the moulding process.
A further method used is the over moulding of the connector onto a clip and conduit, where the clip is attached to one end of the conduit. Here the clip is partially annular in shape and is placed over and in between a cut made in the outer wall of the conduit, therefore the clip sits in between the bead. A connector is then moulded around the clip and conduit. With this method the conduit is often compressed, and with high temperatures and pressures used during moulding excess plastic flashing can be forced from the mould across the connector to the outer wall of the tubing.
Plastic flashings and hot plastic, may during moulding touch the outer wall of the conduit at the connector interface causing damage to the tubing walls, leading to water and air seepage into and out of the conduit.